I'm putting my vote in for Detroit. 20 minutes into the invasion the people of Detroit will be repelling them through hate and bile alone, not to mention the weaponry. Should any invaders land there first they'll either pack up and go home, or wipe the city from the map. I'm not sure which, but it'll be a heck of a show either way...

I think I would like to visit Finland, lots of good music, lots to drink and beautiful northern environment. So I guess Helsinki although I'm sure there are lots of smaller towns that would be awesome to see.